PSA Interpretation and Testing Can Be Made More Effective

NEW YORK--Although it has revolutionized the early detection of
prostate cancer, PSA testing can, and must, be improved to become
the powerful tool needed in the fight against this disease, H.
Ballentine Carter, MD, said at a conference on prostate cancer
at Lenox Hill Hospital.

"PSA testing is virtually synonymous with diagnosis today.
It is the most sensitive indicator we have, though not the most
specific," said Dr. Carter, associate professor of urology,
Johns Hopkins Medical School. The main issue is its inability
to unerringly distinguish between prostate cancer and benign prostatic
hypertrophy (BPH), he said.

Cancer or BPH?

Currently, the most effective way to optimize interpretation of
PSA levels is to look at the rate of PSA change, Dr. Carter said.
He pointed out that although PSA levels vary with both prostate
cancer and BPH, the deviation between consecutive PSA measurements
relative to elapsed time is distinctively different between the
two conditions.

Less than 5% of men without prostate cancer have increases in
PSA greater than 0.75 ng/mL per year; therefore, an increase greater
than this should raise suspicion of prostate cancer, Dr. Carter
said. Accurate interpretation requires at least three measurements
at an interval of no less than 6 months and, ideally, 9 months
to a year.

"That means it would take almost 2 years to accumulate a
good PSA history," he said, adding that "if more men
start having PSA at age 50, it will be reasonable and feasible
to do this."

He also promoted age-specific PSA standards (rather than level
alone) as a means of decreasing false positives in older men and
increasing detection in younger men.